Electronic storage tube control system



June 15, 1954 2 Sheets-Sheet 1 Filed Dec. 15, 1948 EEG Now

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ELECTRONIC STORAGE TUBE CONTROL SYSTEM 2 Sheets-Sheet Filed Dec. 15, 1948 Patented June 15, 1954 ELECTRONIC STORAGE. TUBE CONTROL SYSTEM Rudolf C. Hergenrother, Westhlewton, Mass assig nor to Raytheon Maniifacturing Company,

Newton, Mass, a corporation" of Delaware Application fieoember 15,1948, Serial No. 65,472

5 Claims. (01. 315-4) This invention relates to electron discharge device, and more particularly to a controldevice for controlling the position of an electron] earn in an information storage tube,"for'exampl'edthe type shown in my copending application, Ser. ,No..,6l,222, filed, December 8, l% 8,now Patent Number 2,5{l8jl89} issued April 10, 1951.

ln'storage tubesystems of the type disclosed in said copending application, it is extremely difflcult to acourately'locate particular points on the target area Therefore, when information has been stored at a particular'pointon the target by directing the electron beam thereto and charging said spot with said" beam, it .is difficul't to again locate that particular spot on the target so that the information thereon may be read and used. The difficulty lies in the fact that any changes in the power supply or the deflection generator voltage causes a change in the position of the beam. Furthermore, the smaller the area to.be located, the closer the tolerance must be in the variations in voltage and other circuit parameters.

In addition, when a series of memory unitsare used, there is, no way of insuringthat' theinformation on each tube wouldbe read in correct synchronisinto that of the other tubessince as aforestated the voltage and other circuit parameters of the tubes might varybetween the time when the information was applied to the tube and, the time the information was read off from the tube. Further, when tubes w e interchanged as, forexample, when replacernent was necessary, it was required that the systembe recalibrated to conform to any slight variations in the structure of the replacement tubes.

Accordingly, it is an object of the present invention to provide a control device whereby memory tubes may have their electron beams repeatedly and accurately positioned on any particular spot on the target.

,A ther o jec o h n nti n i st r vi a co tr l d v c w ic w l lim na hcnecessih of having a restricted storage spaceon thestorage target or. the memory tub I ea h part ula pieceof information but rather the storage surface may be continuous so that the pattern of storage elements .is not restricted or preassigned.

Stillanother object ,of this invention is to provide a control device whereby several memory tubes may be synchronized so thattheir respec- K 1 im er' etsu e ileum???- ly positioned, in any ,particnlarspot on their respective target surfaces.

tion will b estbe understood by reference to the of; and to the accompanying drawings, wherein: Fig. l'represents one modification of the invention wherein information positioned at any particular point onthe'storage surface maybe located at will; and Fig. 2 represents a furthermodification of my invention wherein the storage target area may be scanned repeatedly over precisely th 'sa me in the scanning raster. Referring now to Fig. 1, there is disclosed a vertical sweep monitor tube ill and a' horizontal sweepmonitor tube '2 l controlling the jsweep'circuits which feed the deflection platesbf'aninformation storage unit schematically shown "at l3'having an information storage surface 13a."

It is to be clearly understood thatjthe circuit described is by way of illustration only and any desired control circuit may be used'in conjunction with the monitor tubes and memory unit. Furthermore, while the preferred rn'odi:licati n of my invention employs two monitor'tubes, one for the vertical sweep, and one for the'shorizon'tal 5 "sweep, this is not absolutely necessary'sin'ce both units could be consolidated into 'a'sin'gle imonitor tube havingboth'hor'izorital and jv'e'rtitfaldefl ection plates and horizontal and verticalrnonitoring slots in the target' .The vertical monitor tube [0 comprises an electron gun I4, consisting'of a cathode l5; a grid jothe'r' endto the grid [6 and a source of negative potential of roughly 1500 volts. The correct density and. focus of, the beam projected from the gun M are produced by connecting the cathode I5 and the focusing anode ll'to suitable taps on the resistor 50.

d [The beam is deflected vertically in response, to voltage applied between a 'pair of "deflecting plates I9, one of which is connected'to" ground I and the other of which is connected' to a suitable deflection voltage generator 2B. The beam is directed towardan electrode 21 consistingl'ofa fiat I, plate with a series of horizontal slots out 'therein and which is connected to 'grourid'fpote'ntial. lilehi'nd thiselectrode z l is 'a jsecgnd conductin ectr e. 21 Suc ha when. l'i eam gdire i tow rd a is e in t plat Z' f [will I pass the're'through and jstrike 'th'ej adj acent electrode 22'; The electrode"?! is connected to ground through a load resistor 23. A shield 41 surrounds the space between the deflection plate i9 and the electrode 2| to prevent external electric field. from afiecting the electron beam.

Thus it may be seen that if the beam is moved vertically it will pass over the slots in the electrode 2 i, and each time it crosses one of the slots a stream of electrons will strike the electrode 22 causing an output voltage pulse to appear across the resistor 23.

The output voltage pulses developed across the resistor 23 are fed into a counting circuit 3| which may be any of the counting circuits well known in the art, for example, a ring counter, wherein a series of electron tubes are successively turned on or off by a series of pulses until, when a certain number of pulses have been received, a particular tube conducts, producing a large output pulse. In this case the number of pulses is preset, for example, by a train of pulses introduced to the counting circuit for that purpose. The output from the counting circuit 3! is used to trigger electronic switch 24 which, for example, may be of the triggered multivibrator type wherein two tubes are used in a circuit such that, if the grid of one is triggered by a positive pulse, it will cause that tube to conduct and the other tube to be cut 013?. Then when a positive pulse is introduced onto the grid of the tube which is cut off, it will cause that tube to conduct and the first-mentioned tube to be cut off. The output from the switch, which may, for example, be taken from one of the plates through a suitable blocking condenser, is used to apply a rectangular pulse to the grid 25 of a constant current generator which acts as the deflection voltage generator to feed the deflection plates [9 by charging up the capacitance between the plates. The constant current generator circuit 20 consists of a pentode whose plate is attached directly to the ungrounded plate of the monitor tube It. The suppressor grid 26 of the pentode is connected directly to the cathode 2? which is connected to ground through a battery 45 which maintains the oathode at a potential of a few hundred volts negative with respect to ground. The screen 28 is grounded. The grid is normally maintained below cutofi by being connected to the cathode 2! through a grid resistor 29 and a bias battery 30.

Upon the application of a positive pulse from the electronic switch 24 to the grid 25 of the deflection voltage generator 26 the tube is caused to conduct, charging the capacitance existing between the two deflection plates IQ. This causes the beam to sweep across the slots in the electrode 2i producing output pulses on the electrode 22. When a certain number of pulses are received by the counter circuit 3!, it triggers the grid which is below cutoff potential of the electronic switch 2d, causing a negative pulse output to cut oi the generator 20. The deflection voltage applied to the plates I8 remains there and the electron beam remains positioned on the slot which produced the last pulse which triggered the counting circuit.

Thus it may be seen that, by presetting the counting circuit 3| by a train of pulses such that it will count up to a predetermined number of pulses, the electron beam can be made to sweep across that number of slots on the electrode 2! and be automatically halted in position on the slot corresponding to the last pulse. In order that the deflection beam may be reset to zero to begin counting to a difierent position, a retrace circuit 32 is used.

This retrace circuit comprises a gas tube having a plate 33 which is attached to ground through a battery 3!; such that the plate is maintained at a suitable constant positive potential above ground. The cathode 35 is connected directly to the ungrounded deflection plate IS. A screen grid 36 is maintained at a suitable operating voltage above the cathode 35, for example, volts, by means of a battery 31. The grid 38, upon being triggered by a positive pulse from the reset circuit, will cause the tube to fire, thus discharging the capacitance between the plates is until a value is reached where the voltage drop across the gas tube is so low that it ceases to fire. This deflects the beam vertically downward. The voltage of battery 34 is chosen such that the beam comes to rest at a. point below the lowest slot in the electrode 2 I. This represents the beams zero or starting point. The gas tube will then not fire again until its grid is again triggered by a zero reset pulse.

The plates is are directly attached to corresponding vertical deflection plates 46 of the memory unit It, whose action is more completely described in the aforementioned copending application. The horizontal deflection plates 46b of the memory unit it are connected directly to corresponding deflection plates I91) of a horizontal monitor tube 5 I which is in all respects similar in operation to the vertical monitor system. The various components of the horizontal monitor tube system are numbered similarly to those of the vertical monitor tube system with the addition of the suiflx b.

To locate any particular spot on the storage plate (not shown) of the storage unit 53, its characteristic location numbers are set up in the counter circuits 3! of the vertical monitor tube system and 3!?) of the horizontal monitor tube system. For example, if it is wished to locate a point on the target which corresponds to four slots up on the vertical monitor tube screen and seven slots over from the zero position in the horizontal monitor tube screen, the counting circuit 3i would be set to count four pulses before producing an output and the counting circuit 311) would be set to count seven pulses. The respective electronic switches 24 and 242) are then triggered simultaneously to produce positive output pulses, thus starting scanning circuits. The vertical monitor tube will cause the vertical scanning circuit to stop after hitting the fourth slot, and the horizontal counting circuit will stop the horizontal scanning circuit after hitting the seventh slot. Since the plates of the memory unit are connected in parallel with the plates of the monitor tubes, the beam of the memory unit will be accurately positioned on the storage target at a position corresponding to four slots vertical and seven slots horizontal deflection.

Thus it may be seen that, when it is desired to store information on the storage target on a particular spot, for example, the above-mentioned position four vertical, seven horizontal, the beam of the storage unit is positioned thereon by the monitor units and the information storage operation is then carried out. If sometime later, for example, days or weeks, it is desired to read the information stored on this particular spot, the coordinates four vertical and seven horizontal are again set up in the counting circuits and the beam is then automatically and with extreme accuracy repositioned on the spot where the information was stored.

While I have shown here a monitor tube target electrode system comprising a slotted. electrode 2l andzasignal electrode :22, 'it will be obvious to those skilled in the art that other electrode arrangements maybe used for producing output pulses when scanned by a'beam. For example, a

target-electrode mightconsist of two materials having different secondary emission properties, for: example, a background material :of aluminum with lines of carbon on its face in place of slots. *Due'ito (the different secondary emission characteristics, different target currents will occur whenithebeamstrikeseach of the-two materials.

.Referringnow to Fig. 2, there is shown an embodiment of'my invention whereinthe scanning generators. repeatedly .scan precisely the same path. Herein there exists a vertical-monitor tube l:0-.-which.is essentially'similar to that of Fig. 1.

.:However, the electrode 22 is'divide'd into two elecatrodeszz and 22a, theelectrode 22being struck :by-ielectrons passing through anyof the. slots in ;the;electrode. 2 except. theuppermost. Electrons passing through the uppermost slot strike the electrode 22a. The scan. and retrace; circuits "26 :andI32 are precisely the sameas that of 1 .andthe deflection plates. are connected to.corressponding deflection plates of a memory .unit 13.

The output of the electrode 22 is developedacross The output of the Now'an .input trigger pulse for starting the sequence of events is fed through a mixer circuit lfl to trigger the electronic switch2 i to cause-a positive output therefrom. This initiates the scanning by the generator 20. The beam of monitor tube Ill which, .due to. the zero reset action described inFigi 1, is below thelowest slot in the electrode 2| moves upward, crossing the first slot. "The output pulse appearing on electrode 22 feeds through the"mixer-39 to trigger theielec- 'tronic switch 24, stopping the'scan generator. The output from electrode 22 also triggers-the electronic switch 241) which initiates the'sca-n- Ilitig circuit" b ofthe-horizontal monitor-system II. "that of'Figwl except that the electrode 2! has only two vertical slots which are spaced apart by a-distance-equal to the desired length of the horizontal sweep. Behind each of these slots is r The horizontal monitor "tube is similar to an electrode 22b and 220.

The horizontal scan generator 2% is similar to that of Fig. 1. However, the retrace circuit uses a vacuum tube rather than a gas tube. This tube 18 has its plate 49 tied to ground through a plate supply battery 50, its suppressor grid 5! tied to the cathode 52 which is connected directly to the ungrounded deflection plate I91) of the monitor tube II. The screen grid 53 of tube 48 is maintained at a suitable positive potential with respect to the cathode 52 by a battery 54 connected therebetween. The grid 55 is maintained below cutoff by being connected to the cathode 52 through a grid resistor 56 and a bias battery 51.

An electronic switch 4! having its inputs connected to the electrodes 22b and 220, respectively, feeds a positive pulse to the grid 55 of the retrace tube 48 when the beam of monitor tube H produces a pulse on electrode 220, thus initiating the retrace.

position. electronic switchAZ, causing a negative pulse ;,to

duces a-pulse thereon, but-with noefiect since the retrace circuit is already stopped. Thence!)- ning proceeds until the beam ,has -.c-rossed the electrode :2I reaching the -other =slot, whereupon it producesan-output on the electrode 220. The

output from this; electrode is;fed to thenegatiue pulse, grid circuit of the electronic switch -,2,-ilb,

thus;st,0pping the--scanning circuit. The-,pulse is also fed to the start circuit pf an eleo onjc switch M which, as already described, c ergization of the retrace tube 43 cau beam to be deflected back tow ards,i ts or g nal position.

Upon striking theslot in front of the electrode 22b, an output pulse appearscn saidelectro e which feeds a pulse to the negativeoutp grid of the electronic switch 4| stopping the race The beam is then positioned on the slot in front of electrode 22b.

At the same time that thebeam of the horizontal scan. is retracing, the, pulseifrom-electrode 220 is fed through the mixer 40 to;the, start; -grid of the electronic switch24 initiatingscanningby the vertical scan generator. ,This,prod.uc.e s a diagonal retrace on the target ,of the; memory unit [3.

It is essential, in this particular circuit, that the retrace of the horizontalscan generatorbe complete before the vertical scan beamreaches the next slot in its target electrode,2i,-.so that the vertical scan generator 2% will be incendition to be again triggered by the output-from the electrode 22.

This cycle automatically continues until the vertical sweep generatormoves thebeam to the uppermost slot of the electrode 2 i causing a pulse to appear on the electrode 220.. Since no trigger pulse is fed the electronic switch 213b,. the horizontalscan generator 2iibremains in its retraced The output from.22a,is fed into be fed to the grids of both the monitor tubes with the result that. their electron beamsarecut oif. The electronic switch 42 .also feeds a positive ,pulse, through adifferentiating, circuit,-.,which creates a sharp, pip, to the gas tubejn the re yace circuit 32 of the vertical monitortube deflection system lil, thus causing the vertical 'cleflection plates H) to move the beam back to its original starting position. The beam will then remain there until an input trigger pulse again starts the vertical scan generator. This input pulse is simultaneously fed to the opposite grid of the electronic switch 42 from that connected to the electrode 22a. This removes the cutoff pulse applied to the grids of the monitor tubes. The resultant negative pulse applied through the differentiating circuit 43 has no effect on the retrace generator circuit 32 since the gas tube is already cut off.

Thus it may be seen that every time an input trigger pulse is fed into the circuit, the system will cause the storage target of the memory unit to be scanned along a predetermined path. Thus information may be stored on the device It by initiating the scanning action and continuously storing information on the target. Later when it is desired to reread the information the scan 7 sequence is then initiated and the information will again appear in its correct sequence.

It may be noted that the information may be recorded by operating the scanning system at a high speed and then later reading the information at a much slower rate by slowing down the scanning speed of the deflection generators to a slower speed.

It is to be clearly understood that the particular scanning raster used herein is by way of example only and any desired scanning raster may be used. For example, the well-known scan may be used where the horizontal sweep would move the beam across the target, the vertical scan would then raise the beam by one line, and the horizontal scan would move back across the target. The vertical scan would then raise the beam another line and the horizontal beam would scan across the target again. This process would be repeated until the top of the target had been reached, whereupon the vertical retrace occurs as heretofore described.

It is to be clearly understood that the aforementioned illustrations of my invention are by way of example only and other modifications will be apparent to those skilled in the art. Therefore, it is desired that the appended claims be given a broad interpretation commensurate with the scope of the invention within the art.

What is claimed is:

1. A memory device comprising information storage means comprising a charge retaining surface, means for storing information on said storage means, and means for directing said storing means to a particular storage position comprising an electron discharge device having a source of electrons and an electrode, and means for directing electrons from said source to a position on said electrode corresponding to said particular storage position, said electron directing means being functionally related to said storing means directing means.

2. A memory device comprising information storage means comprising a charge retaining surface, means for storing information on said storage means, and means for directing said storing means to a particular storage position comprising an electron discharge device having a source of electrons and an electrode, means for beaming said electrons toward said electrode, and means for controlling the position of said beamed electrons and said means for directing said storing means in response to any predetermined one of a group of numbers of output pulses 8 from said electrode, said electron directing means being functionally related to said storing means directing means.

3. A memory device comprising information storage means comprising a charge retaining surface, means for storing information on said storage means, and means for directing said storing means to a particular storage position comprising an electron discharge device having a source of electrons and an electrode, means for forming said electrons into a sharply defined beam, means for directing said electron beam to various positions on said electrode, and means for controlling said electron beam and said means for directing said storing means in response to the output from said electrode.

4. A memory device comprising an electron discharge device having a source of electrons and a storage plate, means to direct said electrons to particular positions on said plate to store thereon charges representative of information comprising a second electron discharge device having a source of electrons and an electrode, means for directing said electrons toward said electrode, and means for simultaneously controlling the electron directing means in both said electron discharge devices.

5. A memory device comprising an electron discharge device having a source of electrons and a storage plate having a homogeneous surface, means to direct said electrons to particular positions on said plate to store charges representative of information comprising a second electron discharge device having a source of electrons and an electrode, means for directing said electrons toward said electrode, and means for simultaneously controlling the electron directing means in both said electron discharge devices in response to output signals from said second electron discharge device.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,976,400 Ilberg Oct. 9, 1934 2,417,450 Sears Mar. 18, 1947 2,441,296 Snyder, Jr., et a1. May 11, 1948 2,446,945 Morton et a1. Aug. 10, 1948 2,451,484 Gould et al. Oct. 19, 1948 2,454,410 Snyder, Jr. Nov. 23, 1948 2,457,911 Munster Jan. 4, 1949 2,474,628 Hurvitz June 28, 1949 2,474,811 Arditi et a1. July 5, 1949 

